Hydraulic ramming apparatus

ABSTRACT

A hydraulic ramming apparatus including an apparatus body (14) having a cylinder bore (23) and a guide bore (24) that are successively formed to each other in the apparatus body (14). A piston (30) is slidably inserted into the cylinder bore (23) so as to be reciprocable within the cylinder bore (23). An upper pressure-receiving chamber (31) is defined at an upper end portion side of the piston (30), and a lower pressure-receiving chamber (32) is defined at a lower end portion side of the piston (30). A ramming tool (19), having a rod body (35), can be detachably inserted into the guide bore (24). Also, a mechanism for moving the rod body (35) is provided so as to follow upward movement of the piston (30).

TECHNICAL FIELD

The present invention relates to a hydraulic ramming apparatus forramming and use in a state in which it is attached to an arm or the likeof a hydraulic shovel-type excavator.

BACKGROUND ART

As a hydraulic ramming apparatus, various types of ramming apparatus(devices) are well known.

For example, a hydraulic ramming apparatus disclosed in Japanese UtilityModel Publication No. Hei 6-21923 is well known. In this hydraulicramming apparatus, a piston is slidably inserted into a cylinder boreformed in an apparatus (device) body so as to enable the piston tovertically move within the cylinder bore, and to thereby define an upperpressure chamber and a lower pressure chamber. In addition, the pistonis protruded downwardly from the device body, and a ramming plate isattached to the protruded end portion thereof. Further, a change-overvalve for switching circuits of pressurized oil is provided in thedevice body.

In the hydraulic ramming apparatus, when the change-over valve isswitched by the vertical movement of the piston and the pressurized oilis alternately supplied to or discharged from the upper pressure chamberand the lower pressure chamber to vertically move the piston, theramming plate is vertically moved to thereby ram or compact the ground.

However, in the hydraulic ramming apparatus thus constructed, since theramming plate is attached to the protruded end portion of the pistonwhich is vertically movable by the hydraulic pressure, the rammingapparatus is applied to only the ramming or compacting work and theapparatus is not available, for example, for crushing work using achisel.

That is, in a case where rocks or the like are crushed by utilizing thechisel, when the chisel in a state of being abutted against rocks or thelike is hammered by the vertical movement of the piston and impactpoints on the rock by the chisel is converged to one point, the rocks orthe like can be efficiently crushed.

However, as described above, when the chisel is attached to theprotruded end portion of the piston, the chisel is liable to verticallymove together with the piston, and the impact points of the chiselagainst the rock are apart from each other in every hammering operationand thus the impact points cannot be converged, so that it is difficultto efficiently crush the rocks.

In addition, in the hydraulic ramming apparatus described above, theremay be posed a problem that a lateral force is liable to be applied ontoa sliding portion of the piston and the lateral force will damage thesliding portion of the piston, which may result in oil leakage.

Namely, when the ground is subjected to the ramming operation by usingthe vertically moving ramming plate, the lateral force other than upwardreactive force is also applied to the ramming plate due toirregularities of the ground. The lateral force is transmitted to thepiston, and the piston is obliged to vertically slide within thecylinder bore while the piston is obliquely impressed to the cylinderbore formed in the device body, so that there may be a case where thesliding portion of the piston is damaged. When the sliding portion ofthe piston is damaged, there may cause a problem that the pressurizedoil charged in the upper and lower pressure chambers leaks, thusresulting deteriorated reliability of the device.

In addition, the piston of the above-mentioned hydraulic rammingapparatus comprises the sliding portion and the protruded end portion,so that an entire length of the piston will become large and it requiressignificant amounts of time to work and assemble the piston system.

That is, the sliding portion of the piston is required to be subjectedto a precision work and a heat-treating work so as to prevent thepressurized oil from leaking therefrom. However, since the entire lengthof the piston sliding portion long, an initial set-up for the workbecomes complicated and will disadvantageously prolong the working timeof the piston assembly.

Furthermore, a dimensional tolerance between the piston sliding portionand the cylinder bore is extremely small and both the piston and thecylinder bore are strictly required to be aligned in a straight line andthe piston is required to be inserted into the cylinder bore with a highdegree of accuracy. However, the entire length of the piston becomeslong due to existence of the protruded end portion as described above,so that the inserting operation cannot be performed easily whichprolongs the assembling time for the device.

Therefore, the present invention is achieved for solving theaforementioned problems and an object of the present invention is toprovide a hydraulic ramming apparatus which and is also applicable to acrushing operation using a chisel or the like, and is substantially freefrom the oil leakage and enables the working time to be shortened andthe assembling time.

SUMMARY OF THE INVENTION

In order to achieve the afore-mentioned object, the hydraulic rammingapparatus according to the present invention includes an apparatus bodyhaving a cylinder bore and a guide bore that are successively formed toeach other in the device body. A piston is slidably inserted in thecylinder bore so as to be reciprocable within the cylinder bore. Anupper pressure-receiving chamber is defined at an upper end portion sideof the piston, and a lower pressure-receiving chamber is defined at alower end portion side of the piston. A ramming tool, having a rod body,is detachably inserted into the guide bore and a mechanism for movingthe rod body is provided so as to follow upward movement of the piston.

Further, the mechanism for moving the rod body so as to follow thepiston is constructed to be detachable, and the guide bore is formed soas to allow the end portion of the chisel to be detachably inserted intothe guide bore in place of the ramming tool.

In the construction described above, since the piston and the rod bodyof the ramming tool are separately formed, it becomes possible to insertthe end portion of the chisel in place of the rod body, and thus theapparatus can be available not only for a ramming operation but also fora crushing operation.

Further, on the basis of the same reason, even if the rod body isinclined against an elastic force of an elastic member when a lateralforce is applied to the ramming tool during the ramming working, thelateral force will not be transmitted to the piston, so that the slidingportion of the piston will not be damaged.

Furthermore, the piston can be individually worked under a condition ofbeing separated from the ramming tool, and the piston can also beindividually inserted into the cylinder bore, so that it becomespossible to shorten the working time and the assembling time of thedevice.

The following are examples of the mechanism for moving the rod body soas to follow the piston described above, 1) a spring for urging the rodbody towards the piston, 2) a hydraulic cylinder device is providedbetween the rod body and the device body, and 3) a flexible cylindricalbody for connecting the rod body and the end portion of the piston arepreferable.

In this regard, the spring can be attached in such a manner that thespring is interposed between a spring receiving portion and a springreceiver which is slidably inserted in the rod body and is formed to beengageable with the device body. Then the spring receiver is engagedwith or disengaged from the device body while the spring is in a stateof being compressed.

In another way, the spring can also be attached in such a manner thatthe spring is interposed between a spring receiving portion and a guidering which is slidably inserted into the rod body and is formed to beengageable with the device body. A removable ring is then fitted to aposition of the rod body, the position being outside the guide ring,thereby to compress the spring, and the guide ring together with thecompressed spring are attached to the device body, thereafter theremovable ring is removed from the rod body.

Further, in the construction described above, it is preferable toconstruct the apparatus in such a manner that an elongated recessedportion is provided at the rod body, and a pin positioned in a directionnormal to the rod body is rotatably fitted into the device body so thatthe pin passes through the elongated recessed portion, thereby to allowan outer circumferential surface of the pin to contact the surface ofthe elongated recessed portion. In another way, it is preferable thatthe elongated recessed portion is provided at the rod body, and asupporting shaft oriented in a direction normal to the rod body isrotatably fitted to the device body, and a roller is rotatably fitted tothe supporting shaft so that the roller passes through the elongatedrecessed portion, thereby to allow an outer circumferential surface ofthe roller to contact with the surface of the elongated recessed portionand not to contact the device body.

Furthermore, in the construction described above, the ramming apparatuscan also be constructed so that the upper pressure chamber is connectedto a hydraulic tank through a change-over valve and a restrictor. Inthis construction, when the rod body of the ramming tool is insertedinto the guide bore, the change-over valve is switched and the upperpressure-receiving chamber is connected to the hydraulic tank throughthe restrictor, while at any other time, the upper pressure chamber iscut off from the hydraulic tank.

As another way, the apparatus can also be constructed so that anauxiliary pressure-receiving chamber is connected to the upperpressure-receiving chamber and the auxiliary pressure-receiving chamberis also connected to the hydraulic tank through the change-over valveand the restrictor. In this construction, when the rod body of theramming tool is inserted into the guide bore, the change-over valve isswitched whereby the auxiliary pressure-receiving chamber is connectedto the hydraulic tank through the restrictor, while at any other time,the auxiliary pressure-receiving chamber is directly connected to thehydraulic tank.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more apparent and more easilyunderstood from the following detailed description when taken inconjunction with the accompanying drawings in which preferredembodiments of the present invention are shown by way of illustrativeexamples.

Further, the embodiments shown in the accompanying drawings are not forspecifying or limiting the scope of the present invention, but aremerely for facilitating the explanation and understanding of thisinvention.

In the accompanying drawings:

FIG. 1 a longitudinal sectional view showing one embodiment of ahydraulic ramming apparatus according to the present invention;

FIG. 2 is a sectional view taken along the line II--II of FIG. 1;

FIG. 3 is a sectional view taken along the line III--III of FIG. 1;

FIG. 4 is an exploded perspective view showing a first example of aspring mounting portion used in the embodiment shown in FIG. 1;

FIG. 5 is a sectional view showing an embodiment in which a chisel isattached;

FIG. 6 is a sectional view showing a second example of a spring mountingportion;

FIG. 7 is a plan view showing a detachable ring of the spring mountingportion shown in FIG. 6;

FIG. 8 is a view showing a cross sectional portion close to an elongatedrecessed portion of a rod body in a hydraulic ramming apparatus;

FIG. 9 is a sectional view showing a third example of a spring mountingportion;

FIG. 10 is a sectional view showing a fourth example of a springmounting portion;

FIG. 11 is a sectional view showing a fifth example of a spring mountingportion;

FIG. 12 is a sectional view showing a sixth example of a hydrauliccylinder mounting portion corresponding to a spring mounting portion;

FIG. 13 is a sectional view showing another example of a structure for arod body to follow up to a piston;

FIG. 14 is a sectional view showing a first example of a mechanism forvertically moving a piston;

FIG. 15 is a schematic view showing a first example of a mechanism forvertically moving a piston;

FIG. 16 is a sectional view showing a second example of a mechanism forvertically moving a piston;

FIG. 17 is a schematic view showing a second example of a mechanism forvertically moving a piston;

FIG. 18 is a view showing a longitudinal section of a third example of amechanism for vertically moving a piston; and

FIG. 19 is a schematic view showing a principal structure of a fourthexample used in a mechanism for vertically moving a piston.

DETAILED DESCRIPTION OF THE INVENTION

The preferred embodiments of the hydraulic ramming apparatus (device)according to the present invention will now be described with referenceto the accompanying drawings.

As shown in FIG. 1, an apparatus (device) body 14 comprises an upperbody 20, a lower body 21 fitted to a lower end portion of the upper body20 and a cap body 22 is fitted to an upper end portion of the upper body20. A cylinder bore 23 is formed in the upper body 20 so as tovertically pass through the upper body 20, and a guide bore 24 is formedin the lower body 21 so as to vertically pass through the lower body 21,while the cap body 22 is provided with a bore 25. The bore 25, thecylinder bore 23 and the guide bore 24 are coaxially connected to eachother.

A piston 30 is slidably inserted into the cylinder bore 23 so that anupper pressure-receiving chamber 31, a lower pressure-receiving chamber32 and a drain port 33 are defined. Further, an upper end portion of thepiston 30 is slidably inserted into the bore 25 of the cap body 22. Inthis connection, for the purpose of increasing the speed of the piston30 moving downwardly, a chamber 34 formed in the bore 25 may be filledwith nitrogen gas or the like so that the piston is pushed downwards.The piston 30 may also be pushed downwards by the action of a spring,not shown.

An upper end portion of a rod body 35 is slidably inserted into theguide bore 24 enabling the rod body to vertically move within the guidebore 24. A longitudinal elongated recessed portion 36 is formed at aside surface of a top end portion of the rod body 35. A pin 37,extending in a direction normal to the lower body 21, is provided so asto pass through the elongated recessed portion 36. The pin preventsrotation of the rod body 35 so that the rod body can not rotate around acentral axis thereof. The lower end portion of the rod body 35 protrudesdownwards from the lower end portion of the lower body 21, and a rammingplate 38 is detachably attached to the protruded portion by means of apin 38a, thus constituting a ramming tool 19.

The rod body 35 described above is upwardly pushed or biased by means ofan elastic member such as spring 40 so that the upper end surface 35a ofthe rod body 35 normally abuts against the lower end surface 30a of thepiston 30. When the piston 30 is vertically moved, the rod body 35 isalso vertically moved so as to follow the piston 30, so that the rammingplate 38 is vertically moved thereby to ram the ground.

In this regard, if the spring 40 is not provided, the rod body 35 willmove downwards due to its own weight, and the upper end surface 35a ofthe rod body 35 will be apart from the lower end surface 30a of thepiston 30 when the piston 30 is moved upwards. As a result, the piston30 is vertically moved while the ramming plate 38 is held in a state ofbeing in contact with the ground, so that it is impossible to ram theground by vertically moving the ramming plate 38.

Next, a first example of an attachment structure of the spring 40 willbe explained.

As shown in FIG. 1, a cylindrical body 43 having an upper flange 41 anda lower flange 42 is attached to the lower end surface of the lower body21 by fastening the upper flange 41 by means of bolts 44. As shown inFIGS. 2, 3 and 4, the lower flange 42 of the cylindrical body 43 has apair of straight-line-shaped outer surfaces 45, and a pair ofcircular-arc-shaped outer surfaces 46. The paired straight-line-shapedouter surfaces 45 are formed at portions to be rotatively symmetric toeach other at a symmetric angle of 180° with respect to a center of thelower flange 42. The paired circular-arc-shaped- outer surfaces 46 areformed at portions rotated at an angle of 90° from thestraight-line-shaped outer surfaces 45, and the pairedcircular-arc-shaped outer surfaces 46 are rotatively symmetric at 180°with respect to the center of the lower flange 42. In addition, anengaging recessed portion 47 is formed at an upper portion of respectivecircular-arc-shaped outer surfaces 46.

As shown in FIG. 1, at an almost central portion of the rod body 35, aring-shaped spring receiving portion 48 is provided. The springreceiving portion 48 can be integrally formed with the rod body 35, orseparately formed and attached to the rod body 35 by means of bolts, pinor the like.

As shown in FIG. 1, a cylindrical spring receiver 49 comprising a smallsized cylinder 50 and a large sized cylinder 52 integrally formed withan upper portion of the small sized cylinder 50 is loosely engaged withthe lower end portion of the rod body 35. The spring receiver 49 has aring-shaped protrusion 51 integrally formed on an inner surface of thelower portion of the small sized cylinder 50, while a pair of engagingprotruded portions 53 are integrally formed on an inner surface of theupper portion of the large sized cylinder 52. The engaging protrudedportions 53 are formed at portions to be rotatively symmetric to eachother at a symmetric angle of 180°. When the engaging protruded portions53 are engaged with engaging recessed portions 47 formed in the lowerflange 42 of the cylinder body 43, the spring receiver 49 is connectedto the cylinder body 43 so as not to rotate. Further, a spring 40 isinterposed between the ring-shaped protrusion 51 and the springreceiving portion 48 thereby to push up the rod body 35 by the action ofthe urging force of the spring 40.

Next, an operation for inserting the rod body 35 into the lower body 21will be explained.

At first, under a state where the ramming plate 38 is detached from therod body 35, the spring receiver 49 is inserted into the lower portionof the rod body 35, and the spring 40 is provided between thering-shaped protrusion 51 and the spring receiving portion 48.

Then, when the upper end portion of the rod body 35 is inserted into theguide bore 24 of the lower body 21, the pin 37 is rotatably fitted intothe lower body 21 so as to pass through the elongated recessed portion36 thereby to lock the rod body 35 so as to prevent rotation.Subsequently, the positions of the paired engaging protruded portions 53of the spring receiver 49 are adjusted so that the engaging protrudedportions 53 face the paired straight-line-shaped outer surfaces 45.Thereafter, the spring receiver 49 is moved upwards while the spring 40is compressed, and the positions of the paired engaging protrudedportions are adjusted so as to be higher than that of the lower flange42.

In such a state, the spring receiver 49 is rotated around a central axisat a rotation angle of 90°, and the positions of the paired engagingprotruded portions 53 are adjusted to those of the engaging recessedportions 47. In this state, when a worker detaches his hand from thespring receiver 49, the spring receiver 49 moves downwards by the actionof the urging force of the spring 40. As the result, the paired engagingprotruded portions 53 are engaged with the engaging recessed portions 47respectively, and the cylinder body 43 is connected to the springreceiver 49.

In this regard, in a case where the rod body 35 is required to be drawnout, it is sufficient to perform works in reverse to those describedabove.

Further, as shown in FIG. 5, after the rod body 35 is drawn out from anapparatus body 14 of a vibration generator 13, when a base end portionof a chisel 58 is inserted into the guide bore 24 of the lower body 21,then the chisel 58 is locked by means of the pin 37, the chisel 58 movesdownwards under its own weight and the upper end surface of the chisel58 is spaced apart from the lower end surface 30a of the piston 30. Inthis state, when the piston 30 is vertically moved, the piston 30repeatedly strikes the base end portion of the chisel 58, thus enablinga crushing operation to be performed. As a result, the working device ofthis invention can also be used as an ordinary chisel-type breaker.

By the way, the upper end portion of the chisel 58 has the same shape asthat of the upper portion of the rod body 35, and a cut-out recessedportion 59 is formed at a side surface of the upper end portion of thechisel 58 for allowing the pin 37 to pass therethrough.

In this regard, in the case of the attachment structure of the spring 40described above, not only force for lifting the rod body 35 but alsoforce for compressing the spring 40 are required when the rod body 35 isattached or detached. Therefore, a large operation force isdisadvantageously required. However, if the following attachmentstructure (second example) of the spring 40 is adapted, the requiredoperation force can be reduced to a small level.

As shown in FIG. 6, prior to the insertion of the rod body 35 into theguide bore 24, the spring 40 is previously assembled into the rod body35. Namely, a snap ring 107 is fitted to the lower portion of the rodbody 35, and a detaching ring 108 shown in FIG.7 and a guide ring 109are fitted so that the detaching ring 108 and the guide ring 109 arepositioned at a level higher than that of the snap ring 107. A spring40, in a state of being compressed to have a set length, is interposedbetween the guide ring 109 and the spring receiver 48. In addition, theguide ring 109 is fitted to the lower portion of the lower body 21. Thelock pins 110 are inserted into the boundaries between the guide ring109 and the lower body 21 whereby the guide ring 109 can from droppingout from the lower portion of the lower body 21.

Accordingly, as described above, after the rod body 35 is inserted intoguide bore 24 of the lower body 21, the lock pin 110 is inserted intothe boundary portion between the lower end portion of the lower body 21and the guide ring 109. Finally, when the detachable ring 108 is pulledaway, an attaching operation of the rod body 35 to the lower body 21 iscompleted. At this time, since the operator is required only to lift upthe rod body 35, the required operating force can be reduced.

Further, as described above, the pin 37 is passed through the elongatedrecessed portion 36 formed in a longitudinal direction at the sidesurface of the upper portion of the rod body 35 so that the pin 37 isfitted in a direction normal to the lower portion 21, thus resulting ina construction in which the rod body 35 can not freely rotate around thecentral axis thereof.

In a hydraulic ramming apparatus having such a construction, when theapparatus is used for ramming a rough ground, an axial rotating force isgenerated due to a rotation torque to be caused at the ramming plate 38,to that either one of both corner portions of the elongated recessedportion 36 is pushed to an outer peripheral surface of the pin 37 withan excessively large force, and a reaction force against the excessivelylarge force is applied from the lower body 21 to the pin 37. As theresult, the pin 37 will not rotate and the rod body 35 will slideagainst the pin 37, so that abrasion or wear of both membersdisadvantageously progresses. In spite of the situation described above,when the pin 37 is obliged to rotate, the pin 37 would slide against thelower body 21 while the pin 37 is applied with the large reaction forcefrom the lower body 21, so that the wear of both members will progress,thereby to pose a problem that the rod body 35 and the pin 37 aredamaged in a short period of time.

In addition, when a friction force between the rod body 35 and the pin37 becomes large, a rotational resistance at the time of the rod body 35being reciprocated will also become excessive, so that it becomesimpossible for the rod body 35 to follow the movement of the piston 30by depending on only the urging force of the spring 40. As a result, therod body 35 will disorderly move, so that it may become impossible toperform the ramming work. However, if the following construction isapplied, the problems described above will be effectively solved.

FIG. 8 is a cross sectional view showing the construction. In FIG. 8, alateral bore 21a is formed in the lower body 21 so as to pass throughthe lower body 21 in a direction normal to the rod body 35, and aspindle 112 having a plug 111 with a collar screwed into one end of thespindle 112 is inserted into the lateral bore 21a. At the other end ofthe spindle 112, a ring pin 113 for preventing the spindle 112 fromdrawing out from the lateral bore 21a is attached so as to pass throughthe spindle 112. In addition, a roller 114 is rotatably supported by asmall-sized central portion of the spindle 112, so that an outerperipheral surface of the roller 114 contacts a surface of the elongatedrecessed portion 36 formed in the rod body 35.

In addition, at a center axial portion of the spindle 112, there isformed a lubricating bore 112a into which a lubricating oil is filled.The filled lubricating oil is prevented from leaking by a plug 111screwed to an end portion of the lubricating bore 112a, and thelubricating oil is supplied to a portion between the small-sized centralportion of the spindle 112 and the roller 114. At both the sides of theroller 114 i.e., at the ring pin 113 side of the spindle 112 and theinner side of the plug 111, there are attached an oil seal 116 and aretainer ring 117 for retaining the oil seal 116, respectively. Further,an O-ring 118 is fitted and attached to a portion between the one endportion of the spindle 112 and the plug 111. Furthermore, a cutoutclearance 21b is formed at an inner peripheral portion of the lateralbore 21a which is opposed to the rod body 35, so that the outerperipheral surface of the roller 114 does not contact an innerperipheral surface of the lateral bore 21.

According to the construction shown in FIG. 8, when the rod body 35 isreciprocated by the reciprocating movement of the piston 30, the roller114 also reciprocally rotates due to the reciprocal movement of the rodbody 35.

At this time, for example, even in a case where rotary torque isgenerated at the ramming plate 38 thereby to generate an axial rotatingforce in the rod body 35 and either one of both corner portions of theelongated recessed portion 36 is strongly pressed onto the outerperipheral surface of the pin 37 with a large excessive force, theroller 114 can freely rotate so as to follow reciprocal movement of therod body 35 because the cutout clearance 21b is formed at the innerperipheral portion of the lateral bore 21a which is opposed to the rodbody 35 so that the outer peripheral surface of the roller 114 would notcontact to the inner peripheral surface of the lateral bore 21.

Accordingly, of course, there is no occurrence of the wear of the innerperipheral surface of the lateral bore 21, and the wear of the roller114 and the rod body 35 can be also remarkably reduced, and the usefullives of these parts can be prolonged and maintenance work for theseparts can also be simplified.

Further, since the roller 114 can freely rotate so as to follow up thereciprocal movement of the rod body 35, a friction force between the rodbody 35 and the pin 37 will become small and the rotating resistance ofthe rod body 35 at the time of reciprocation will also be small.Accordingly, it becomes possible for the rod body 35 to fully followmovement of the piston 30 by the action of only the urging force of thespring 40. As a result, the rod body 35 will not disorderly move and itbecomes possible to easily perform the ramming work.

Next, other examples of structures for attaching the spring 40 will beexplained.

FIG. 9 shows a third example of the spring attachment structure in whicha flange 90 is integrally formed with the spring receiver 49. The flange90 is directly fastened and fixed to the lower end portion of the lowerbody 21 by means of bolts 91.

FIG. 10 shows a fourth example of the spring attachment structure inwhich a female screw portion 92 is formed on an inner surface of anupper end portion of the spring receiver 49 and the female screw portion92 is engaged to a male screw portion 93 formed on the outer peripheralsurface of upper end portion of the lower body 21, so that the springreceiver 49 is attached to the lower body 21.

As another way, FIG. 11 shows a fifth example of the spring attachmentstructure in which a ring 95 having a plurality of brackets 94 is fixedto the lower end portion of the lower body 21 by means of bolts. A ring96 for attaching the spring is integrally formed with the rod body 35 orthe ring 96 is attached to the rod body 35. Then, the ring 96 and eachof the brackets 94 are connected to both ends of the spring 40respectively, so that the rod body 35 is urged upwards by the force ofthe spring 40.

In each of the examples described above, the spring is used as anelastic member. However, other elastic members such as a combinationformed by combining a plurality of disc springs, a rubber material,resin material having a resiliency can also be used as the elasticmember. In this case, these elastic members are attached to the rod body35 in the same manner as in the case of the spring.

Furthermore, as the other examples of the elastic member, an expandablyurged type cylinder or a contractibly urged type cylinder such as a gascylinder, a pneumatic cylinder, a hydraulic cylinder having a functionof accumulating pressure may also be used. In such a case, as shown inFIG. 12 as a sixth example, a cylinder tube 98 of a cylinder 97 may beconnected to the lower body 21 while a piston 99 is connected to the rodbody 35.

Next, the other examples of constructions for allowing the rod body 35to follow the piston 30 will now be explained.

As shown in FIG. 13, a protruded portion 100 is integrally formed at thelower end portion of the piston 30, and the upper end portion of the rodbody 35 is abutted against the protruded portion 100. Thereafter, boththe members are connected to each other by means of a flexible coupling101.

The flexible coupling 101 is assembled in such a manner that both endportions of a cylindrical body 102 composed of flexible material such asrubber or the like are fitted into the protruded portion 100 and theupper end portion of the rod body 35. Then, the fitted portions arefixed by means of bolts 103, respectively. The flexible coupling 101 maybe substituted for an universal joint.

In addition, at a portion of the lower body 21 opposing the connectedportion, there is formed an opened window portion 104 through which theconnecting or separating operation of the cylindrical body 102 can beeasily performed. The opened window portion 104 is normally closed by acover 105. The piston 30 and the rod body 35 may be formed integrally.

Next, the mechanisms for vertically moving the piston 30 will beexplained hereunder.

(FIRST EXAMPLE)

As shown in FIG. 14, a large diameter portion 30a, a small diameter rodportion 30c positioned at the upper side of the large diameter portion30a and a small diameter rod portion 30b positioned at the lower side ofthe large diameter portion 30a are formed with the piston 30 which isslidably inserted into the cylinder bore 23. The upperpressure-receiving chamber 31 has a large pressure-receiving area whilethe lower pressure-receiving chamber 32 has a small pressure-receivingarea.

In addition, a spool 61 is slidably inserted into a spool bore 60 formedin the upper body 20 thereby to constitute a change-over valve 62. Apump port 63, a main port 64 and a tank port 65 are formed in the spoolbore 60 while a first pressure chamber 66 and a second pressure chamber67 are formed at both end sides of the spool 61, respectively.

The spool 61 functions to establish communication between the pump port63, the main port 64 and the tank port 65 and block communicationtherebetween. When the spool 61 is pushed and moved to a first positionby the pressurized oil filling in the first pressure chamber 66 having alarge diameter, the main port 64 and the tank port 65 are connected toeach other while communication between the pump port 63 and the mainport 64 is blocked.

In contrast, when the spool 61 is pushed and moved to a second positionby the pressurized oil filled in the second pressure chamber 67 having asmall diameter, the pump port 63 and the main port 64 are connected toeach other while communication between the main port 64 and the tankport 65 is blocked.

The tank port 65 is normally connected to a drain port 33 formed in thecylinder bore 23, and the first pressure chamber 66 is connected to anauxiliary port 68 formed in the cylinder bore 23. The auxiliary port 68is connected to or shut off from the drain port 33 and a first port 70thereby to constitute a servo valve 71. Further, the main port 64 isconnected to a second port 72, and the pressurized oil delivered from ahydraulic pump 73 is supplied to the first port 70 and the pump port 63.

The mechanism described above can also be schematically expressed asshown in FIG. 15. The first port 70 is commonly used in both the servovalve 71 and the lower pressure-receiving chamber 32.

The function of the mechanism is as follows.

When the piston 30 is positioned at an intermediate position as shownFIGS. 14 and 15, the drain port 33, the auxiliary port 68 and the firstport 70 are cut off by the action of the switching piston 69. Onepressurized oil then fills the first pressure chamber 66, so that thespool 61 takes the first position A, thus the main port 64 iscommunicated with the tank port 65.

Under these conditions, when the piston 30 is moved upwards (a directionshown by an arrow) within a predetermined distance by the action of thepressurized oil filled in the lower pressure-receiving chamber 32, thesmall diameter portion 69a of the switching piston 69 allows theauxiliary port 68 to connect to the drain port 33, and the pressurizedoil filling in the first pressure chamber 66 is supplied to a tank 78.As a result, the spool 61 takes the second position B by the action of apressure accumulated in the second pressure chamber 67, so that the pumpport 63 is communicated with the main port 64.

Due to these operations, when the pressurized oil is supplied to theupper pressure-receiving chamber 31 and the piston is moved downwards ina predetermined distance by the action due to a difference in thepressure-receiving areas between the upper pressure-receiving chamber 31and the lower pressure-receiving chamber 32. The large diameter rodportion 30b of the piston 30 allows the auxiliary port 68 to connect tothe first port 70 thereby to supply the pressurized oil to the firstpressure chamber 66. Then, the spool 61 of the change-over valve 62takes the first position A by the action due to a difference in thepressure-receiving areas between the first pressure chamber 66 and thesecond pressure chamber 67, so that the piston 30 moves upwards.Thereafter, the sequential operations described above are repeated.

(SECOND EXAMPLE)

As shown in FIG. 16, a sub-port 74 is formed in the spool bore 60. Afirst communicating port 75 and a second communicating port 76 areformed in the cylinder bore 23, respectively. An axial bore 77 is formedin the spool 61, so that the pressurized oil flowed into the pump port63 flows into the sub-port 74 through the axial bore 77. Then, thepressurized oil flowed out from the sub-port 74 flows into the firstpressure chamber 66 through the first communication port 75 and theauxiliary port 68.

The mechanism described above can also be schematically expressed asshown in FIG. 17. The change-over valve 62 is constructed as a four-portand two-position valve. When the change-over valve 62 takes the secondposition B, the sub-port 74 is communicated with the tank port 65.

Next, the function of this mechanism will be explained hereunder.

When the piston 30 takes an intermediate position shown in FIGS. 16 and17, the first communication port 75 is connected to the auxiliary port68, and the pressurized oil flowed out from the pump port 63 flows intothe first pressure chamber 66 through the axial bore 77, the sub-port74, the first communication port 75 and the auxiliary port 68, so thatthe spool 61 takes the first position A. Then, the pressurized oilflowed out from the upper pressure-receiving chamber 31 flows into thedrain port 33 through the second port 72, the main port 64 and the tankport 65, so that the piston 30 moves upwards (a direction shown by anarrow) by the action of the pressurized oil flowed into the lowerpressure-receiving chamber 32.

When the piston 30 is moved to an upper stroke end position, the firstcommunication port 75 is shut off and the auxiliary port 68 is connectedto the drain port 33, so that the pressurized oil filling in the firstpressure chamber 66 flows into the tank 78, and the spool 61 takes thesecond position B by the action of the pressurized oil filling in thesecond pressure chamber 67. As a result, the pressurized oil in the pumpport 63 flows into the upper pressure-receiving chamber 31 through themain port 64 and the second port 72, so that the piston 30 movesdownwards.

When the piston 30 is moved to a lower stroke end position, the firstport 70 is communicated with the second communication port 76, so thatthe pressurized oil flowed out from the auxiliary port 68 flows into thefirst pressure chamber 66. As a result, the spool 61 takes the firstposition A, so that the piston 30 moves upwards. Thereafter, thesequential operations described above are repeated.

In this way, the second pressure chamber 67 of the change-over valve 62is normally connected to the pump port 63 and the first pressure chamber66 is alternatively connected to the pump port 63 and the drain port 33,so that the spool 61 will not malfunction. Accordingly, the piston 30can be securely reciprocated.

That is, while the piston 30 is moved downwards from the upper strokeend position by a predetermined distance, the first pressure chamber 66is connected to the tank 78. Under this condition, even if thepressurized oil filling in the lower pressure-receiving chamber 32 leaksfrom a clearance between the cylinder bore 23 and the piston 30, apressure is not generated in the first pressure chamber 66.

In addition, even if the piston 30 is moved downwards to a positionfurther than the predetermined distance thereby to shut off theauxiliary port 68, the pressurized oil leaking from the clearance flowsinto the tank 78 through the second communication port 76, the firstcommunication port 75, the sub-port 74, the tank port 65 and the drainport 33, so that a pressure is not generated in the first pressurechamber 66. Accordingly, the spool 61 of the change-over valve 62 wouldnot move to the first position A.

(THIRD EXAMPLE)

As shown in FIG. 18, there is provided a low pressure circuit 121 forconnecting the upper pressure-receiving chamber 31 of a vibrationgenerator 13 to the tank 78 through a restrictor 120, and a switchingvalve 122 for connecting/shutting off the low pressure circuit 121 isprovided. The change-over valve 122 takes a connecting position j by anurging force of a spring 123, and takes a shutting-off position k when asolenoid 124 is energized.

In a case where the ramming work is performed using such example, thechange-over valve 122 is set to take the connecting position j withoutenergizing the solenoid 124. Then, the upper pressure-receiving chamber31 of the vibration generator 13 is connected to the tank 78 through therestrictor 120. Owing to this operation, a part of the pressurized oilflowed into the upper pressure-receiving chamber 31 flows out to thetank 78 through the restrictor 120, so that the pressure in the upperpressure-receiving chamber 31 would not abruptly increase but moderatelyincrease. Namely, when the piston 30 is moved downward and the rammingplate 38 is in contact with the ground, the pressure in the upperpressure-receiving chamber 31 would not abruptly increase. Accordingly,the apparatus body 14 and the piston rod 12 are not rapidly lifted, sothat a large shock or impact would not be applied to the arm, a boom andan upper car body through the pressurized oil contained in a buckethydraulic cylinder of a working machine, not shown, and the buckethydraulic cylinder, and thus a riding feeling for an operator can beimproved.

Further, in a case where the crushing operation will be performed byusing the apparatus to which the basic end portion of the chisel 58 isattached in place of the ramming tool 19 as shown in FIG. 5, thechange-over valve 122 is set to the shut-off position k by energizingthe solenoid. At this time, communication between the upperpressure-receiving chamber 31 of the vibration generator 13 and the tank78 is blocked, so that the pressure in the upper pressure-receivingchamber 31 increases to a high level. Accordingly, a force for impactingthe basic end portion of the chisel 58 by using the piston 30 becomeslarge, so that the crushing operation can be efficiently performed.

(FOURTH EXAMPLE)

As shown in FIG. 19, a ramming apparatus of a fourth example isconstructed so as to be provided with an auxiliary pressure-receivingchamber 125. Further, the auxiliary pressure-receiving chamber 125 isconstructed so as to establish communication between the main port 64 ofthe change-over valve 62 and the tank 78 so as to be switchable by theaction of the change-over valve 126. That is, the change-over valve 126is switchable to a first position 1 and a second position m. When thechange-over valve 126 takes the first position 1, the auxiliarypressure-receiving chamber 125 is connected to the main port 64, and isalso communicated with the tank 78 through the restrictor 127. Further,when the change-over valve 126 takes the second position m,communication between the auxiliary pressure-receiving chamber 125 andthe main port 64 is blocked, and the auxiliary pressure-receivingchamber 125 is directly communicated with the tank 78.

When the change-over valve 126 is set to the first position 1 at thetime of the ramming working, the pressurized oil is supplied to theupper pressure-receiving chamber 31 and the auxiliary pressure-receivingchamber 125. At the same time, the upper pressure-receiving chamber 31and the auxiliary pressure-receiving chamber 125 are communicated withthe tank 78 through the restrictor 127. Accordingly, the piston 30 ispushed downwards by the action of the pressurized oil supplied to boththe upper pressure-receiving chamber 31 and the auxiliarypressure-receiving chamber 125, so that the difference between thepressure-receiving area for generating a force to push the piston 30downwards and the pressure-receiving area for generating a force to pushthe piston 30 upwards becomes large. As a result, a force i.e., theramming force for pushing the piston 30 downwards becomes large.

In addition, the upper pressure-receiving chamber 31 and the auxiliarypressure-receiving chamber 125 are communicated with the tank 78 throughthe restrictor 127, so that the pressures in the both the upperpressure-receiving chamber 31 and the auxiliary pressure-receivingchamber 125 is not abruptly increased, and thus the riding feeling ofthe operator can be improved in the same manner as in the third example.

Further, in a case where the crushing operation will be performed byusing the apparatus to which the chisel 58 is attached as shown in FIG.5, if the change-over valve 126 is set to the second position m, theauxiliary pressure-receiving chamber 125 is communicated with the tank78, so that the pressurized oil is supplied only to the upperpressure-receiving chamber 31. Accordingly, the pressure-receiving areafor generating a pressure to push the piston 30 downwards becomes small,so that a moving speed of the piston 30 is increased.

In addition, the amount of the pressurized oil to be supplied to theupper pressure-receiving chamber 31 can be increased by an amountcorresponding to the amount of the pressurized oil not to be supplied tothe auxiliary pressure-receiving chamber 125, so that the pressure inthe upper pressure-receiving chamber 31 becomes large. Therefore, theforce for impacting the base end portion of the chisel 58 by using thepiston 30 becomes large, so that the crushing operation can beefficiently performed.

In the examples described above, the pressurized oil is normallysupplied to the lower pressure-receiving chamber 32, and the upperpressure-receiving chamber 31 is supplied with the pressurized oil orconnected to the tank so that the piston 30 is vertically moved due tothe difference in the pressure-receiving areas of the upperpressure-receiving chamber 31 and the lower pressure-receiving chamber32. However, the present invention is not limited to such examples, theramming apparatus can also be constructed so that the upperpressure-receiving chamber 31 and the lower pressure-receiving chamber32 are alternatively connected to a hydraulic power unit and the tankthereby to vertically move the piston 30.

As described above, according to the hydraulic ramming apparatus of thepresent invention, since the piston 30 and the rod body 35 of theramming tool 19 are separately formed, it becomes possible to insert thebasic end portion of the chisel 58 in place of the rod body 35, and thusthe ramming apparatus can be available not only to the ramming operationbut also for a crushing operation.

Further, from the same reason, even if the rod body 35 is inclinedagainst the elastic force of an elastic member when a lateral force isapplied to the ramming tool 19 during the ramming working, the lateralforce will not be transmitted to the piston 30, so that the slidingportion of the piston 30 will not be damaged.

Furthermore, the piston 30 can be individually worked under a conditionof being separated from the ramming tool 19, and the piston 30 can alsobe individually inserted into the cylinder bore 23, so that it becomespossible to shorten the working time and the assembling time of theramming apparatus.

Although the present invention has been described with reference to theexemplified embodiments, it will be apparent to those skilled in the artthat various modifications, changes, omissions, additions and othervariations can be made in the disclosed embodiments of the presentinvention without departing from the scope or spirit of the presentinvention. Accordingly, it should be understood that the presentinvention is not limited to the described embodiments and shall includethe scope specified by the elements defined in the appended claims andthe scope equivalent to the claims.

What is claimed is:
 1. A hydraulic ramming apparatus assemblycomprising:a cylindrical body defining a cylinder bore and a guide boreextending from said cylinder bore, a piston slidably inserted in saidcylinder bore so as to be reciprocal therein, and upper and lowerpressure-receiving chambers defined between an inner peripheral surfaceof said cylindrical body and an outer peripheral surface of said piston;a ramming tool having a rod body which is removably inserted into saidguide bore of said cylindrical body; a chisel which is alternativelyremovably mounted to said guide bore of said cylindrical body in placeof said ramming tool; a mechanism for mounting said remming tool to saidcylinder body and for resiliently biasing moving said rod body towardsaid piston, said mechanism being removably connected to saidcylindrical body to permit removal of said rod body and insertion andcoupling of said chisel in said bore; and means for alternately mountingsaid ramming tool or said chisel in said guide bore.
 2. A hydraulicramming apparatus as claimed in claim 1, wherein said mechanism formoving said rod body is mounted at a first end of said cylindrical bodyso as to be aligned with said guide bore.
 3. A hydraulic rammingapparatus as claimed in claim 2, wherein, upon removal of said mechanismfor moving said rod body and said rod body from said cylindrical body,said chisel can be inserted into and secured in said guide bore in amanner such that the chisel will not move in response to movement ofsaid piston away from the chisel.
 4. A hydraulic ramming apparatus asclaimed in claim 1, wherein said mechanism for moving said rod bodycomprises:a spring receiver connected to a first end of said cylindricalbody, said spring receiver defining a large cylinder portion engagingsaid first end of said cylindrical body and a small cylinder portionextending from said large cylinder portion; and a spring disposed insaid spring receiver for biasing said rod body into contact with an endface of said piston.
 5. A hydraulic ramming apparatus as claimed inclaim 1, wherein said rod body of said ramming tool and an upper portionof said chisel are each provided with an elongated recessed portioncooperating with said means for alternatively mounting said ramming toolor said chisel.
 6. A hydraulic ramming apparatus as claimed in claim 5,wherein said mounting means comprises a pin rotatably fitted in saidcylindrical body and extending through said elongated recessed portionof said ramming body or said chisel so that said pin is received in saidelongated recessed portions.
 7. A hydraulic ramming apparatus as claimedin claim 6, wherein said pin extends in a direction normal to alongitudinal direction of said rod body or said upper portion of saidchisel.
 8. A hydraulic ramming apparatus kit comprising:a cylindricalbody defining a cylinder bore and a guide bore extending from saidcylinder bore, a piston slidably inserted in said cylinder bore so as tobe reciprocal therein, and upper and lower pressure-receiving chambersdefined between an inner peripheral surface of said cylindrical body andan outer peripheral surface of said piston; a ramming tool having a rodbody which can be selectively mounted in said guide bore of saidcylindrical body; a chisel which can be selectively mounted in saidguide bore of said cylindrical body in place of said ramming tool; meansfor alternately mounting said ramming tool or said chisel in said guidebore; and a mechanism connectable to said cylindrical body to mount saidramming tool to said cylinder body and to effect movement of said rodbody in a direction toward said piston in response to movement of saidpiston in a direction away from said rod body, wherein said mechanismcan be detached from said cylindrical body to permit removal of said rodbody and insertion, coupling and use of said chisel.